There is no $ shown on steemit.com
It is STU, but they use the dollar sign. It's in the FAQ.

"A post that shows a reward of $10 currently distributes an amount of Steem that is worth about 10 SBD."
I am quite sure that this is not correct. 10 SBD is 49 Steem right now. This would mean you get 25 Steem as the author for a 10 STU post.